Sliding block with adjustable track positioning

Abstract: A sliding block (11) with adjustable track positioning comprising a prismatic body, in one face of which there is a longitudinal recess (12) arranged to receive a rail (13) by way of rolling elements (16) positionable in respective tracks (14,14'), the body being essentially of C-shaped cross-section consisting of a central part (17) from which two flanges extend, wherein in at least one of the two flanges of the C-shaped cross-section there is provided a second longitudinal recess (18) which divides it into separate portions (19,20) connected together at the central part (17), the second recess (18) containing elements (21) for adjusting the distance between the two separate portions (19,20).

Description: This invention relates to a sliding block with adjustable track positioning. Linear sliding guide units generally comprise two main constituent elements, namely an inner element and an outer element slidable relative to each other by way of rolling elements. The inner element is of prismatic shape whereas the outer element is of C-shape, the recess of which carries the inner element. The former is usually known as the rail while the latter is known as the sliding block. A required basic characteristic of the sliding block is that its rolling tracks for the rolling elements be of adjustable distance apart. This adjustment has two main purposes, namely to adapt the distance between the tracks to the type and size of the rolling element used, and to enable the user to directly adjust the loading or the slack. In this respect in sliding blocks formed by extrusion, as the distance between the tracks can vary within a range of a few tenths of a millimetre as allowable tolerance in accordance with the relevant standards, the exact distance must be able to be reset. In addition the user must be able to choose the most suitable slack or preload condition for his specific requirements. In known linear sliding units this is not always possible or is inherently difficult because of their structure. GB-A-2 109 479 discloses a sliding block in a linear bearing unit according to the preamble of claim 1. The object of the present invention is to provide a sliding block in which the distance apart of the rolling element tracks can be adjusted in order to be able to use the prechosen best operating condition. This object is attained according to the present invention by a sliding block according to claim 1. The characteristics and advantages of a sliding block according to the present invention will be more apparent from the description given hereinafter by way of non-limiting example with reference to the accompanying schematic drawings, in which: Figure 1 is a partly sectional elevation of a linear sliding unit using a sliding block with adjustable track positioning according to the present invention; Figure 2 is a partly sectional top plan view of the sliding block shown in Figure 1; With general reference to Figure 1, this represents an elevational view of a linear sliding unit using a sliding block with adjustable track positioning according to the present invention. The figure shows specifically a sliding block, indicated overall by 11, within a recess 12 of which there is located a rail 13. Both the sliding block 11 and the rail 13 are provided in facing surfaces with tracks 14 and 15 respectively, for receiving rolling elements such as balls 16. Both the sliding block 11 with its recess 12 and the rail 13 extend in a direction which will be known as the longitudinal direction. Neither the rail 13 nor the balls 16 are represented in figure 2, for ease of description and comprehension. As stated, the sliding block 11 has a prismatic body, one face of which, for example the upper face, contains the recess 12 for receiving the rail 13. The body is essentially of C-shaped cross-section and thus consists of a central part 17 from which there extent two flanges, which also lie in said longitudinal direction. According to the present invention, one of the two flanges is divided by a variously shaped second recess 18, also lying in the longitudinal direction, into two separate portions 19 and 20 which are connected together in a region extending laterally from the central part 17. A recess 18 could also be provided in the other flange of the sliding block in like manner. Said second recess 18 contains elements for adjusting the distance between the two separate portions 19 and 20 and indicated overall by 21. It should be noted that in addition one of the two separate portions, in the illustrated example that indicated by 20 and facing the interior of the recess 12, has a smaller cross-sectional thickness than the other portion 19. In this respect, Figures 1 and 2 show an embodiment in which the second recess 18, formed between the separate portions 19 and 20 of one of the two flanges, is of open L-shaped cross-section, ie with an obtuse angle between the two inner parts of the L and the lower end facing the first recess 12. The portion 20 extending from it is connected to the central part 17 of the sliding block by a reduced section 22 which enables the portion 20 to flex so that it can approach or withdraw from the other portion 19. This flexure therefore determines a decrease or increase in the distance between the track 14 provided in this first flange and the track 14' provided in the opposing second flange 23 located at the other end on a lateral extension of the central part 17 of the body of the sliding block 11. In the illustrated embodiment, the adjustment elements 21 consist of a shaft 24 arranged in the longitudinal direction and having an eccentric body inserted into a profiled housing 25 provided in facing surfaces of the two separate portions 19 and 20. The ends of the shaft are provided with seats 26 for hexagonal keys for its rotation. Along the body of the shaft 24 there are provided recesses 27 at which screws 28 are positioned. The screws 28 are arranged perpendicular to the shaft 24, ie in a transverse direction both to the flanges and to the recesses in the sliding block. The head of the screws 28 is housed free to rotate in a seat 29 in the first portion 19, the threaded other end being screwed into a corresponding threaded hole 30 provided in the second portion 20. In the illustrated embodiment the operation of the adjustment elements 21 is extremely simple in that by rotating the shaft 24, the portion 20 of the first flange of the sliding block 11 is caused to approach or withdraw from the second flange 23, so as to vary the distance between the tracks 14 and 14'. Having made this adjustment the shaft can be locked in the chosen position by tightening the screws 28, which pass within the recesses 27 to lock it relative to the body of the sliding block. Moreover, the tightening of the screws 28, which pulls the separate portions 19 and 20 of the first flange together, increases the distance between the tracks 14 and 14', so reducing the preload on the sliding unit to hence create slack conditions. Finally the location of the screws 28, for example three in number and cooperating with the respective three cavities 27, prevents withdrawal of the eccentric shaft 24 from its housing 25, even if the portions 19 and 20 are not tightened together. The tracks 14 and 14' can be shaped to receive different rolling elements such as rollers. The rollers arranged in a row can be positioned either simply one behind the other or mutually crossed in order to be able to support forces of different types. A sliding block and the relative rail according to the present invention can be constructed as an extrusion, in steel or in any other suitable material, and as stated can comprise one or two longitudinal recesses with relative adjustment elements. A sliding block with adjustable track positioning is hence provided according to the invention, which enables the slack and preload conditions of the sliding unit in which it is used to be varied by virtue of the particular form of the body of the sliding block and the use of suitable adjustment elements.

Claims: A sliding block with adjustable track positioning comprising a prismatic body, in one face of which there is a longitudinal recess (12) arranged to receive a rail (13) by way of rolling elements (16) positionable in respective tracks (14, 141, 15), said body being essentially of C-shaped cross-section consisting of a central part (17) from which two flanges extend, whereby in at least one of said flanges of said C-shaped cross-section there is provided a second longitudunal recess (18) which divides it into separate portions (19, 20) connected together at said central part (17), said second recess (18) containing elements (21) for adjusting the distance between said two separate portions (19, 20), wherein said adjustment elements (21) consist of screws (28) arranged transversely to said two separate portions (19, 20) and acting to bring said two portions (19, 20) further apart or closer together, characterised in that said screws (28) pass through a seat (29) provided in a first (19) of said two portions (19, 20) and are screwed into a threaded second seat (30) in the other (20) of said two portions (19, 20), said adjustment elements (21) further comprising a longitudinal eccentric shaft (24) inserted within a relative profiled housing (25) provided in facing surfaces of said two portions (19, 20) and interacting with said transversely arranged screws (28). A sliding block as claimed in claim 1, characterised in that that one (20) of said two separate portions (19, 20) facing said first recess (12) is connected to said central part (17) by a reduced section (22). A sliding block as claimed in claim 1, characterised in that said second recess (18) has a cross-section in the form of an open L with its lower end facing said first recess (12). A sliding block as claimed in claim 1, characterised in that said shaft (24) is provided with recesses (27) for receiving said screws (28). A sliding block as claimed in claim 1, characterised in that said rolling elements (16) are balls. A sliding block as claimed in claim 1, characterised in that said rolling elements are rollers.

Inventors: GALLONE FIORENZO, GALLONE, FIORENZO
Applicants: T M T TRASMISSIONI MECCANICHE, T.M.T. TRASMISSIONI MECCANICHE TORINO S.R.L.
Application year: 1994
Main classification: F16C29
IPC codes: F16C29, B23Q1